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Clean up a couple of ad-hoc computations of the maximum number of tuples

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on a page, as suggested by ITAGAKI Takahiro.  Also, change a few places
that were using some other estimates of max-items-per-page to consistently
use MaxOffsetNumber.  This is conservatively large --- we could have used
the new MaxHeapTuplesPerPage macro, or a similar one for index tuples ---
but those places are simply declaring a fixed-size buffer and assuming it
will work, rather than actively testing for overrun.  It seems safer to
size these buffers in a way that can't overflow even if the page is
corrupt.
This commit is contained in:
Tom Lane 2005-09-02 19:02:20 +00:00
parent 962a4bb69f
commit 35e9b1cc1e
6 changed files with 25 additions and 18 deletions
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6
src/backend/access/gist/gistvacuum.c
View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.6 2005/06/30 17:52:14 teodor Exp $
* $PostgreSQL: pgsql/src/backend/access/gist/gistvacuum.c,v 1.7 2005/09/02 19:02:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -52,7 +52,7 @@ gistVacuumUpdate( GistVacuum *gv, BlockNumber blkno, bool needunion ) {
int lenaddon=4, curlenaddon=0, ntodelete=0;
IndexTuple idxtuple, *addon=NULL;
bool needwrite=false;
OffsetNumber todelete[ BLCKSZ/SizeOfIptrData ];
OffsetNumber todelete[MaxOffsetNumber];
ItemPointerData *completed=NULL;
int ncompleted=0, lencompleted=16;
@ -439,7 +439,7 @@ gistbulkdelete(PG_FUNCTION_ARGS) {
page = (Page) BufferGetPage(buffer);
if ( GistPageIsLeaf(page) ) {
OffsetNumber todelete[BLCKSZ/SizeOfIptrData];
OffsetNumber todelete[MaxOffsetNumber];
int ntodelete = 0;
LockBuffer(buffer, GIST_UNLOCK);

4
src/backend/access/nbtree/nbtree.c
View File

@ -12,7 +12,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.130 2005/05/11 06:24:53 neilc Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.131 2005/09/02 19:02:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -584,7 +584,7 @@ btbulkdelete(PG_FUNCTION_ARGS)
IndexBulkDeleteResult *result;
double tuples_removed;
double num_index_tuples;
OffsetNumber deletable[BLCKSZ / sizeof(OffsetNumber)];
OffsetNumber deletable[MaxOffsetNumber];
int ndeletable;
Buffer buf;
BlockNumber num_pages;

6
src/backend/commands/vacuum.c
View File

@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.313 2005/08/20 00:39:54 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.314 2005/09/02 19:02:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2407,7 +2407,7 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
{
Buffer buf;
Page page;
OffsetNumber unused[BLCKSZ / sizeof(OffsetNumber)];
OffsetNumber unused[MaxOffsetNumber];
OffsetNumber offnum,
maxoff;
int uncnt;
@ -2896,7 +2896,7 @@ vacuum_heap(VRelStats *vacrelstats, Relation onerel, VacPageList vacuum_pages)
static void
vacuum_page(Relation onerel, Buffer buffer, VacPage vacpage)
{
OffsetNumber unused[BLCKSZ / sizeof(OffsetNumber)];
OffsetNumber unused[MaxOffsetNumber];
int uncnt;
Page page = BufferGetPage(buffer);
ItemId itemid;

11
src/backend/commands/vacuumlazy.c
View File

@ -31,7 +31,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.57 2005/08/20 23:26:13 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/vacuumlazy.c,v 1.58 2005/09/02 19:02:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -60,9 +60,6 @@
#define REL_TRUNCATE_MINIMUM 1000
#define REL_TRUNCATE_FRACTION 16
/* MAX_TUPLES_PER_PAGE can be a conservative upper limit */
#define MAX_TUPLES_PER_PAGE ((int) (BLCKSZ / sizeof(HeapTupleHeaderData)))
typedef struct LVRelStats
{
@ -259,7 +256,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
* dead-tuple TIDs, pause and do a cycle of vacuuming before we
* tackle this page.
*/
if ((vacrelstats->max_dead_tuples - vacrelstats->num_dead_tuples) < MAX_TUPLES_PER_PAGE &&
if ((vacrelstats->max_dead_tuples - vacrelstats->num_dead_tuples) < MaxHeapTuplesPerPage &&
vacrelstats->num_dead_tuples > 0)
{
/* Remove index entries */
@ -554,7 +551,7 @@ static int
lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
int tupindex, LVRelStats *vacrelstats)
{
OffsetNumber unused[BLCKSZ / sizeof(OffsetNumber)];
OffsetNumber unused[MaxOffsetNumber];
int uncnt;
Page page = BufferGetPage(buffer);
ItemId itemid;
@ -960,7 +957,7 @@ lazy_space_alloc(LVRelStats *vacrelstats, BlockNumber relblocks)
maxtuples = (maintenance_work_mem * 1024L) / sizeof(ItemPointerData);
maxtuples = Min(maxtuples, INT_MAX);
/* stay sane if small maintenance_work_mem */
maxtuples = Max(maxtuples, MAX_TUPLES_PER_PAGE);
maxtuples = Max(maxtuples, MaxHeapTuplesPerPage);
vacrelstats->num_dead_tuples = 0;
vacrelstats->max_dead_tuples = (int) maxtuples;

4
src/backend/nodes/tidbitmap.c
View File

@ -23,7 +23,7 @@
* Copyright (c) 2003-2005, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.6 2005/08/28 22:47:20 tgl Exp $
* $PostgreSQL: pgsql/src/backend/nodes/tidbitmap.c,v 1.7 2005/09/02 19:02:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -42,7 +42,7 @@
* the per-page bitmaps variable size. We just legislate that the size
* is this:
*/
#define MAX_TUPLES_PER_PAGE ((BLCKSZ - 1) / MAXALIGN(offsetof(HeapTupleHeaderData, t_bits) + sizeof(ItemIdData)) + 1)
#define MAX_TUPLES_PER_PAGE MaxHeapTuplesPerPage
/*
* When we have to switch over to lossy storage, we use a data structure

12
src/include/access/htup.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.76 2005/08/20 00:39:59 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.77 2005/09/02 19:02:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -323,6 +323,16 @@ do { \
#define MaxTupleSize \
(BLCKSZ - MAXALIGN(sizeof(PageHeaderData) + MaxSpecialSpace))
/*
* MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
* fit on one heap page. (Note that indexes could have more, because they
* use a smaller tuple header.) We arrive at the divisor because each tuple
* must be maxaligned, and it must have an associated item pointer.
*/
#define MaxHeapTuplesPerPage \
((int) ((BLCKSZ - offsetof(PageHeaderData, pd_linp)) / \
(MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData))))
/*
* MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
* data fields of char(n) and similar types. It need not have anything